Review Question - QID 220532

This patient presents with a closed left supracondylar humerus fracture and ipsilateral middle 1/3 both-bone forearm fractures (BBFF). This injury pattern is also referred to as a "floating elbow." Given the significant amount of energy required to cause this injury, there is an increased risk of compartment syndrome. Therefore, increased anxiety and need for analgesic medication would prompt emergent surgical intervention with possible compartment release.

Supracondylar humerus fractures (SCH) are the most common traumatic injuries in children and frequently affect kids 5-7 years of age with a 1:1 male-to-female ratio. This is most commonly the result of a fall onto an outstretched hand. This injury has been associated with different nerve neuropraxias, including the anterior interosseous nerve (most common), radial nerve (second most common), and ulnar nerve. Other associated injuries include vascular compromise (5-17% of the time) and ipsilateral BBFFs. When SCH fractures occur with an associated BBFF, there needs to be a high index of suspicion for compartment syndrome. In pediatric patients, the 3 A's (analgesia requirement, anxiety, and agitation) are used to evaluate for compartment syndrome. These fractures are classified using the Gartland classification system, which helps dictate treatment. Type 1 is a nondisplaced fracture, type 2 is a fracture displaced in 1 plane with the posterior cortex intact, and type 3 is a fracture displaced in 2-3 planes without an intact anterior or posterior cortex. Cast immobilization can adequately treat type 1 fractures, whereas types 2 and 3 are commonly treated with closed vs open reduction with percutaneous pinning.

Tharakan et al. performed a prospective level 1 study including 41 children with forearm fractures requiring reduction. The mean age was 9.25 years (4.0-15.4 years). They measured superficial volar, deep volar, and dorsal compartment pressure in both arms. The injured vs normal arm mean measurements were as follows: 19.12 vs 10.22 mmHg in the deep volar compartment, 15.56 vs 12.9 mmHg in the dorsal compartment, and 14.8 vs 9.66 mmHg in the superficial volar compartment. They measured >30 mmHg on the injured side in 15 patients (3 had >45 mmHg measurements), with only 1 patient developing acute compartment syndrome (without sequelae). They conclude that fasciotomies in children under close observation could be delayed despite surpassing the accepted pressure limits for adults (>30 mmHg).

Baghdadi et al. performed a systematic review of floating elbow injuries and their association with pediatric acute compartment syndrome (PACS). Eleven studies were included with 433 patients, and 8/433 (2%) patients developed PACS. Pulseless limbs were found in 4% of patients, and all resolved following reduction. Good to excellent results were reported in 83-100% of patients in this review. They conclude that their results contradict other studies that report a high association of PACS with floating elbow injuries. The overall outcomes associated with these injuries are good and do not reflect the poor outcomes associated with adult floating elbow injuries.

Figure A is a lateral elbow radiograph demonstrating a type 3 supracondylar humerus fracture in a skeletally immature patient. Figure B is an AP forearm radiograph demonstrating transverse middle 1/3 both-bone forearm fractures with ulnar translation.

Incorrect answer choices:
Answer 1: With these high-energy injuries, vascular compromise can occur; however, a thready pulse post-reduction is most likely due to a vascular spasm. Without cyanosis or a cold extremity, this does not require emergent operative intervention. Urgent management the following morning is appropriate.
Answer 2: Persistent paresthesias or neuropraxia of the radial nerve following reduction will not alter the urgency of operative intervention.
Answer 4: AIN neuropraxia would present as an inability to perform an A-OK sign on exam. This would not require urgent surgical intervention, and the procedure can proceed the following day, as nearly all neuropraxias associated with this injury resolve spontaneously.
Answer 5: In children, standard clinical evaluation for compartment syndrome may be unreliable or unobtainable. Typically, the 3 A's (analgesia requirement, anxiety, and agitation) are used instead of the 6P's (pain out of proportion, paresthesias, paralysis, pain with passive stretch, pulseless, and poikilothermia).